Ship hull and vessel with such a hull

ABSTRACT

A ship hull with bulb prow and with bottom which extends without sharp changes from the bulb to the square stern of the hull along continuously bent longitudinal lines and with hull sides which are inclined from the vertical plane from the waterline to the bottom plane.

The present invention relates to a ship hull in the shape of anelongated streamlined body which has a prow which when seen in thehorizontal plane is V-shaped above the waterline of the hull with a bulbunder the waterline at one end and a square stern at the opposite end.The invention also relates to a motor driven cargo vessel with a hull ofthis kind.

Modern cargo vessels with a hull of the type mentioned above have a hullshape which is load capacity optimised. This means amongst others thatthe hull has a nearly flat bottom from the region behind the bulb in theprow to a short distance in front of the square stern where the bottomslants upwards towards the bottom edge of the square stern. The hullsides are completely vertical and pass over to the flat bottom via partscurved with a small radius. The advantages of this shape are obvious in,for example, container vessels, because it is possible to dimension thecargo space of the vessel according to the shape of container so thatthe maximum number of containers can be freighted with least possiblewasted space. The disadvantages are, however, on the one hand that thevessel has a low shape stability and must be ballasted when it sailsunloaded and on the other hand that it is not hydrodynamicallyoptimised.

The purpose of the present invention is to provide a ship hull of thetype mentioned in the introduction which can be hydrodynamicallyoptimised and which has a higher shape stability than a cargo capacityoptimised ship hull so that for example it does not need to be ballastedwhen it sails without cargo.

This is achieved according to the invention by the bottom of the hull,at least between the transition between the bulb and the hull and thewaterline of the square stern, extending without any sharp changes alonglongitudinal lines which are curved over at least the largest part ofthe length and that the hull in cross-section having sides which atleast over the largest part of their vertical extent from the waterlineto the bottom plane are inclined to the vertical plane. With a hull ofthis type a 10% lower towing drag than a classic design of this hullcalculated by the Holtrop-method is achieved but on the other hand itresults in the bottom shape in the space in the fore and after-bodies ofthe hull being unsuitable for cargo such as, for example, containers.

The invention, however, is based on the idea of using such spaces forother purposes than for cargo so that a cargo ship with a hull accordingto the invention can lower the total transport cost compared totransporting in a conventional cargo capacity optimised vessel.

A preferred embodiment of a vessel with a hull according to theinvention has in the forebody a first engine room with a plurality ofdiesel motor driven generators and in the afterbody a second engine roomwith a number of electric motors coupled to two propeller shafts. Avessel with a power requirement of approximately 4000 kW can, forexample, have ten diesel motors each having an output of approximately400 kW which without problem could be accommodated in the front half ofthe vessel, for example under the superstructure of the vessel.

The invention will be described in more detail with reference to theembodiments shown on the annexed drawings, where

FIG. 1 shows a lateral view of the hull of a vessel according to theinvention,

FIG. 2 an enlarged frame plan of the hull in FIG. 1,

FIG. 3 a view from below of the hull of a vessel shown in FIGS. 1 and 2and

FIG. 4 a perspective view of a container cargo vessel with a hullaccording to the invention.

In the Figures reference numeral 1 describes generally a ship's hullwhich has a prow 2 which is V-shaped when seen in the horizontal planeand a flat square stern 3 above the waterline 4. Under the waterline 4the prow has a bulb 5. As is evident from the contour line 6 the bottom7 runs in a continuous gentle curve without any sharp changes from thebulb 5 all the way to the waterline of the afterbody, which in theexample shown forms the bottom edge of the square stern. As a comparisonreference can be made to the chain-dotted line 8 in FIG. 1 which marksthe corresponding bottom contours of a conventional cargo vessel ofmodern design. As is evident in FIG. 1 the line 8 is a straight linefrom the bulb 5 to just before the square stern 3 where it slopesupwards at 9 towards the square stern.

The hull 1 is built up of elongated single curved plates 10 which arewelded together with each other so that the weld seams 10a essentiallyfollow the actual flow direction of the water along the hull. As isespecially evident from FIG. 2 the plates 20 incline under the waterline4 from the vertical plane 11 and the inclination increases continuouslyfrom the waterline 4 downwards towards the bottom surface 12. In orderto show the difference from the shape of the bottom and sides or aconventional cargo ship of modem type the latter has been shown withchain-dotted line 13 in FIG. 2.

The illustrated and described shape of the hull 1 gives the hull agreater shape stability than a conventional hull with the shape which isshown with chain-dotted lines 13 partly because of the larger widthcompared with a conventional hull and partly because of the inclinationof the hull sides. The stability is increased thereby by a factor ofapproximately 2.5 compared with a conventional vessel. The tow drag ofthe hull 1 will be approximately 10% lower than that of a classicdesign.

It is evident from FIGS. 1 and 2 that the hull space in the verticaldirection in the fore and after-bodies of the hull 1, especially in theafter-body, is less than in a conventional hull. This is compensated toa certain extent by the greater width and the greater space between thefore and after-bodies and also by the greater shape stability whichpermits higher deck cargos.

The loss of a certain amount of cargo space in the fore and end bodiescan, however, be further compensated in a vessel with a hull 1 accordingto the invention.

An embodiment is shown in FIG. 3 where details with counterparts inFIGS. 1 and 2 have the same reference numerals as in FIGS. 1 and 2.

In the fore body of the hull 1 in direct contact with the V-shaped prow2 is a first engine room 20 which accommodates a plurality of dieselmotors 21 which are each coupled to an electric generator 22. A vesselwith a power requirement of 4000 kW can for example have ten dieselmotors each producing 400 kW of power. In contrast to a single ship'sdiesel in the power class 4000 kW which requires a large vertical space,the drive machinery 21, 22 shown takes up only a little space verticallyand therefore can be placed in a space directly under the superstructure23 of the vessel, that is to say a space which normally is not usable ascargo space as it is not accessible from above. In the aft body of thehull 1 in the part which is relatively shallow is a second engine room24 which receives a number of electric motors 25 as well as the otherelectrical equipment 26 which is required for the supply of power fromthe generators 22 to the electric motors 25. The electric motors 25drive two propeller shafts 28 via reduction gearings 27. Through thedescribed arrangement the widest part of the hull over a large part ofits length can be used as cargo space. Through its greater width incomparison to a conventional ship's hull with the same length and itsgreater shape stability a vessel with a hull according to the inventioncan take a higher deck cargo which is illustrated in FIG. 3 bycontainers 30 stacked five high.

Further advantages with dividing up the drive machinery into a pluralityof motors in this way are on the one hand there is always poweravailable if one or some of the motors should stop, and on the otherhand that safety is increased if the motors are grouped in severalseparate engine rooms which are fireproof with respect to each other andthe rest of the surroundings.

I claim:
 1. Ship hull for a cargo ship, a passenger ship or the like inthe shape of an elongated streamlined body which has, when seen in thehorizontal plane, a V-shaped prow above the waterline of the hull with abulb under the waterline at one end, and a square stern at the opposingend, characterised in that the bottom lines (6) of the hull (1) extendwithout any sharp changes, at least between the transition from the bulb(5) to the hull and the waterline (4) of the square stern, alonglongitudinal vertical planes, said bottom lines being curved over atleast the greatest part of their length, and that the hull incross-section has sides (10) which are inclined at least over thegreatest part of the vertical extent from the waterline (4) to thelongitudinal vertical midplane (11).
 2. Ship hull according to claim 1,characterised in that the bottom (7) of the hull (1) in a verticalcentral plane (11) in the longitudinal direction extends from the frontend of the bulb (5) to the square stern along a continuously bent line(6).
 3. Ship hull according to claim 1, characterised in that the hull(1) is made up of single curved plates (10) which run in thelongitudinal direction of the hull and which are welded together andthat the seams (10a) run in essentially the direction of the flow ofwater along the hull.
 4. Ship hull according to claim 3, characterisedin that seen in the cross-section through the hull (1) the inclinationof the plates (10) increases from the waterline (4) downwards towardsthe bottom plane.
 5. Vessel with a hull according to claim 1,characterised in that the hull (1) has a first engine room (20) withmachinery (21,22) which is positioned in the front half of the hull. 6.Vessel according to claim 5, characterised in that the hull (1) has asuper-structure (23) which is positioned above the engine room (20). 7.Vessel according to claim 5, characterised in that the machinery in thefirst engine room (20) comprises at least one drive motor and agenerator driven by this and that a second engine room (24) ispositioned in the stern half of the hull and contains at least oneelectric motor (25) which is supplied with power from the generator (22)and coupled to a propeller shaft (28).
 8. Vessel according to claim 7,characterised in that a plurality of diesel motors (21) with associatedgenerators (22) are arranged in the first engine room (20).